# -*- coding: utf-8 -*-

# @Author: Chen Hua
# @Date  : 2019-06-28
# @Desc  : 

import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleep


def check_keydown_events(event, ai_settings, screen, ship, bullets):
    if event.key == pygame.K_RIGHT:
        ship.moving_right = True
    elif event.key == pygame.K_LEFT:
        ship.moving_left = True
    elif event.key == pygame.K_SPACE:
        fire_bulet(ai_settings, screen, ship, bullets)
    elif event.key == pygame.K_q:
        sys.exit()


def fire_bulet(ai_settings, screen, ship, bullets):
    if len(bullets) < ai_settings.bullets_allowed:
        new_bullet = Bullet(ai_settings, screen, ship)
        bullets.add(new_bullet)


def check_keyup_events(event, ship):
    if event.key == pygame.K_RIGHT:
        ship.moving_right = False
    elif event.key == pygame.K_LEFT:
        ship.moving_left = False


def check_events(ai_settings, screen, stats, sb, play_button, ship, aliens, bullets):
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()
        elif event.type == pygame.MOUSEBUTTONDOWN:
            mouse_x, mouse_y = pygame.mouse.get_pos()
            check_play_button(ai_settings, screen, stats, sb, play_button, ship, aliens, bullets, mouse_x, mouse_y)

        elif event.type == pygame.KEYDOWN:
            check_keydown_events(event, ai_settings, screen, ship, bullets)
        elif event.type == pygame.KEYUP:
            check_keyup_events(event, ship)


def check_play_button(ai_settings, screen, stats, sb, play_button, ship, aliens, bullets, mouse_x, mouse_y):
    button_clicked = play_button.rect.collidepoint(mouse_x, mouse_y)
    if button_clicked and not stats.game_active:
        ai_settings.initialize_dynamic_settings()
        pygame.mouse.set_visible(False)
        stats.reset_stats()
        stats.game_active = True
        # 重置记分牌图像
        sb.prep_score()
        sb.prep_high_score()
        sb.prep_level()
        sb.prep_ships()
        # 清空外星人列表和子弹列表
        aliens.empty()
        bullets.empty()
        create_fleet(ai_settings, screen, ship, aliens)
        ship.center_ship()


def update_screen(ai_settings, screen, stats, sb, ship, aliens, bullets, play_button):
    screen.fill(ai_settings.bg_color)
    for b in bullets.sprites():
        b.draw_bullet()
    ship.blitme()
    aliens.draw(screen)
    sb.show_score()
    if not stats.game_active:
        play_button.draw_button()
    # 可见
    pygame.display.flip()


def update_bullets(ai_settings, screen, stats, sb, ship, aliens, bullets):
    # 更新子弹位置
    bullets.update()
    # 删除消失的子弹
    for b in bullets.copy():
        if b.rect.bottom <= 0:
            bullets.remove(b)

    check_bullet_alien_collisions(ai_settings, screen, stats, sb, ship, aliens, bullets)


def check_bullet_alien_collisions(ai_settings, screen, stats, sb, ship, aliens, bullets):
    # 检查子弹是否击中了外星人
    # 如果是这样，就删除相应的子弹和外星人
    collisions = pygame.sprite.groupcollide(bullets, aliens, True, True)
    if collisions:
        for aliens in collisions.values():
            stats.score += ai_settings.alien_points
            sb.prep_score()
        check_high_score(stats, sb)
    # 如果外星人被消灭完了，删除现有子弹并新建一群外星人
    if len(aliens) == 0:
        bullets.empty()
        ai_settings.increase_speed()
        stats.level += 1
        sb.prep_level()
        create_fleet(ai_settings, screen, ship, aliens)


def get_number_rows(ai_settings, ship_height, alien_height):
    # 计算屏幕可以容纳多少外星人
    available_space_y = (ai_settings.screen_height -
                         (3 * alien_height) - ship_height)
    number_rows = int(available_space_y / (2 * alien_height))
    return number_rows


def get_number_aliens_x(ai_settings, alien_width):
    # 计算每行可以容纳多少外星人
    available_space_x = ai_settings.screen_width - 2 * alien_width
    number_aliens_x = int(available_space_x / (2 * alien_width))
    return number_aliens_x


def create_alien(ai_settings, screen, aliens, alien_number, row_number):
    alien = Alien(ai_settings, screen)
    alien_width = alien.rect.width
    alien.x = alien_width + 2 * alien_width * alien_number
    alien.rect.x = alien.x
    alien.rect.y = alien.rect.height + 2 * alien.rect.height * row_number
    aliens.add(alien)


def create_fleet(ai_settings, screen, ship, aliens):
    # 创建一个外星人，并计算每行可以容纳多少个外星人
    alien = Alien(ai_settings, screen)
    number_aliens_x = get_number_aliens_x(ai_settings, alien.rect.width)
    # #创建第一行外星人
    # for alien_number in range(number_aliens_x):
    #     create_alien(ai_settings, screen, aliens, alien_number)
    # 创建外星人群
    number_rows = get_number_rows(ai_settings, ship.rect.height, alien.rect.height)
    print(number_rows, ' ', number_aliens_x)
    for row_number in range(number_rows):
        for alien_number in range(number_aliens_x):
            create_alien(ai_settings, screen, aliens, alien_number, row_number)


def update_aliens(ai_settings, screen, stats, sb, ship, aliens, bullets):
    check_fleet_edges(ai_settings, aliens)
    aliens.update()
    # 检测外星人和飞船之间的碰撞
    if pygame.sprite.spritecollideany(ship, aliens):
        ship_hit(ai_settings, screen, stats, sb, ship, aliens, bullets)
    check_aliens_bottom(ai_settings, screen, stats, sb, ship, aliens, bullets)


def check_fleet_edges(ai_settiongs, aliens):
    # 外星人到达边缘时采取的措施
    for alien in aliens.sprites():
        if alien.check_edges():
            change_fleet_direction(ai_settiongs, aliens)
            break


def change_fleet_direction(ai_settiongs, aliens):
    # 将整群外星人下移，并且改变他们的方向
    for alien in aliens.sprites():
        alien.rect.y += ai_settiongs.fleet_drop_speed
    ai_settiongs.fleet_direction *= -1


def ship_hit(ai_settings, screen, stats, sb, ship, aliens, bullets):
    if stats.ships_left > 0:
        # 将ships_left 减少1
        stats.ships_left -= 1
        # 跟新记分牌
        sb.prep_ships()
        # 清空外星人列表和子弹列表
        aliens.empty()
        bullets.empty()
        # 创建一群新的外星人，并将飞船放到屏幕底部中央
        create_fleet(ai_settings, screen, ship, aliens)
        ship.center_ship()
        sleep(0.5)
    else:
        stats.game_active = False
        pygame.mouse.set_visible(True)


def check_aliens_bottom(ai_settings, screen, stats, sb, ship, aliens, bullets):
    screen_rect = screen.get_rect()
    for alien in aliens.sprites():
        if alien.rect.bottom >= screen_rect.bottom:
            # 像飞船被撞到一样处理
            ship_hit(ai_settings, stats, screen, sb, ship, aliens, bullets)
            break


def check_high_score(stats, sb):
    if stats.score > stats.high_score:
        stats.high_score = stats.score
        sb.prep_high_score()
